With increasing development of science and technology, a variety of electronic devices are designed in views of convenience and user-friendliness. For helping the user well operate the electronic devices, the electronic devices are gradually developed in views of humanization. The common electronic devices include for example notebook computers, mobile phones, satellite navigation devices, or the like. Recently, the storage capacity and the processor's computing performance for these electronic devices are largely enhanced, and thus their functions become more powerful and complicated. For efficiently operating an electronic device, a touchpad is used as an input device of the electronic device for controlling the operations of the electronic device.
FIG. 1 schematically illustrates a conventional notebook computer with a touchpad module. As shown in FIG. 1, the touchpad module 1 is installed on a casing 21 of the notebook computer 2. Moreover, at least a portion of the touchpad module 1 is exposed outside so as to be touched by the user's finger. Consequently, the user may operate the touchpad module 1 to control the notebook computer 2. For example, in case that the user's finger is placed on the touchpad module 1 and slid on the touchpad module 1, a cursor 23 shown on a display screen 22 of the notebook computer 2 is correspondingly moved. Moreover, in case that the touchpad module 1 is pressed down by the user's finger, the notebook computer 2 executes a specified function. The use of the touchpad module 1 can implement some functions of the conventional mouse. In other words, the user may operate the notebook computer 2 through the touchpad module 1 without the need of additionally carrying or installing the mouse.
FIG. 2 is a schematic cross-sectional view illustrating the touchpad module as shown in FIG. 1, in which the touchpad module is not pressed down. FIG. 3 is a schematic cross-sectional view illustrating the touchpad module as shown in FIG. 1, in which the touchpad module is pressed down. FIG. 4 is a schematic cross-sectional view illustrating portions of a circuit board and a switch element of the touchpad module as shown in FIG. 1. As shown in FIGS. 2, 3 and 4, a fixing frame 24 is concavely formed in the casing 21 of the notebook computer 2. A supporting structure 241 and a triggering part 242 are respectively protruded from two opposite sides of an inner wall of the fixing frame 24. A first end 11 of the touchpad module 1 is connected with the supporting structure 241. Consequently, a second end 12 of the touchpad module 1 may be swung relative to the triggering part 242 by using the supporting structure 241 as a fulcrum.
The touchpad module 1 further comprises a switch element 13 and a circuit board 14. The switch element 13 is located under the second end 12 of the touchpad module 1 and aligned with the triggering part 242. The switch element 13 comprises a metal dome 131. A first conducting part 141 and a second conducting part 142 corresponding to the metal dome 131 are disposed on the circuit board 14. The first conducting part 141 and the second conducting part 142 are separated from each other by a gap. When the touchpad module 1 is not pressed down, the metal dome 131 is not subjected to deformation. Meanwhile, as shown in FIG. 4, the metal dome 131 is contacted with the first conducting part 141 but not contacted with the second conducting part 142.
While the touchpad module 1 is pressed down by the user, the second end 12 of the touchpad module 1 is swung downwardly relative to the triggering part 242 by using the supporting structure 241 as a fulcrum. When the switch element 13 of the touchpad module 1 is pushed by the triggering part 242 of the fixing frame 24, the metal dome 131 is subjected to deformation. At the same time, the metal dome 131 is contacted with both of the first conducting part 141 and the second conducting part 142, and the electric connection between the first conducting part 141 and the second conducting part 142 is established. Under this circumstance, the switch element 13 is triggered to generate a switch signal to the notebook computer 2. According to the switch signal, the notebook computer 2 executes a corresponding function. When the touchpad module 1 is no longer pressed by the user, the second end 12 of the touchpad module 1 is swung upwardly relative to the triggering part 242 in response to the elastic force of the metal dome 131 and/or the elastic force of the supporting structure 241. Consequently, the metal dome 131 is restored to its original shape (see FIG. 4) and the touchpad module 1 is returned to its original position.
However, the conventional touchpad module 1 still has some drawbacks. For example, while the touchpad module 1 is pressed down by the user, unpleasant noise is generated. The source of the noise includes the click sound in response to the collision between the switch element 13 and the triggering part 242 and the click sound in response to the collision between the deformed metal dome 131 and the second conducting part 142. For solving this problem, some other touchpad modules have been disclosed. In accordance with a conventional touchpad module, a rubber element (not shown) is disposed on the triggering part 242 to alleviate the collision between the switch element 13 and the triggering part 242. In accordance with another conventional touchpad module, a rubber cover is sheathed around the switch element 13. Due to the rubber cover, the click sound inside the touchpad module is blocked from being outputted from the touchpad module. However, regardless of whether the rubber element is installed on the triggering part 242 or the rubber cover is sheathed around the switch element 13, the efficacy of reducing the noise is limited. In other words, the touchpad module needs to be further improved.